Heat exchanger



March 31, 1970 w N ET AL 3,503,439

HEAT EXCHANGER Filed Sept. 26, 1968 INVENTORS 05/042 54mm 4000- J'A'GER United States Patent M 3,503,439 HEAT EXCHANGER Oskar Wanka, Deggendorf (Danube), and Adolf Jiiger, Plattling, Germany, assignors to Deggendorfer Werft und Eisenbau Gesellscllaft m.b.H., Deggendorf (Danube), Germany Filed Sept. 26, 1968, Ser. No. 762,830

Claims priority, application Germany, Sept. 26, 1967,

Int. Cl. F28f 13/12 U.S. Cl. 165-108 Claims ABSTRACT OF THE DISCLOSURE A heat exchanger has an annular upwardly oriented tube bundle including headers connected with the tubes as opposite ends of the bundle, the bundle and the headers being removable from the installed position as a unit. In its operating state, the unit is surrounded by a heat exchange medium of an apparatus for effecting chemical reactions, and a propeller circulates the heat exchange medium. The heat exchanger extends upwardly into the range of the propeller and one of the headers is circular and closely surrounds the propeller with its inner wall to form a nozzle for the propeller. A current displacer extends upwardly through the interior of the tube bundle and may be traversed by a heat exchange medium or may have internal heating means, whereby to serve as an additional heat exchange surface.

BACKGROUND OF THE INVENTION Heat exchangers comprising a tube bundle and collecting chambers or headers for supply and discharge of one heat exchange medium, and connected with opposite ends of the tubes, can be built as separate apparatus. In general, the space surrounding the tubes and exteriorly defined by a jacket is terminated at both ends by the tube bottom plates, and is provided, in the proximity of these plates, with lateral connections for the supply and discharge of the other heat exchange medium which is conducted in either direct flow or counter flow along the tubes.

There are also heat exchangers which are installed in another apparatus, for example, a contact furnace for carrying out endothermic or exothermic chemical reactions, or which are combined with such apparatus in other ways. In such cases, the space surrounding the tubes of the heat exchanger is filled with a salt mixture which serves as an operating medium for the contact furnace and which preferably is liquid at the operating temperature. In order to attain a good heat transfer, it is customary to circulate the heat carrier of the contact furnace by a stirring mechanism, so that the heat carrier passes cyclically over the contact tubes and the heat exchanger tubes.

SUMMARY OF THE INVENTION This invention relates to heat exchangers and, more particularly, to a novel and improved heat exchanger particularly designed for use with apparatus for effecting chemical reactions.

The invention is directed to a heat exchanger of the type which is operatively associated with a, contact furnace, and the tubes of the heat exchanger are preferably arranged in one or more circular cross section rows.

- Such a heat exchanger may be arranged, for example,

in a central flow or guide tube or conduit of a contact furnace, with a propeller being provided to circulate 3,503,439 Patented Mar. 31, 1970 the heat carrier flowing over the tubes of the heat exchanger. This propeller is generally arranged centrally above the heat exchanger, as shown, for example, in German Patent No. 1,064,922. In the same type of installation, a complete tube system of the heat exchangers has been combined with the propeller and its driving motor to form a common unit for assembly and disassembly, as shown in German Patent No. 1,181,177.

It happens that the variations of the input product, with an increased amount of reaction heat to be eliminated and constant masses of the space available for accommodating the heat exchanger and the propeller, must be taken into consideration. A greater heat exchange can be attained, on the one hand, by increasing the velocity of flow of at least one heat exchange medium and, on the other hand, by increasing the heat exchange surface. Both are possible, since a heat exchanger in accordance with the invention extends upwardly into the range of the propeller. The propeller is surrounded with a relatively small clearance by an annular collecting chamber or header. A current displacer is arranged to extend upwardly through the interior of the heat exchanger tube bundle.

In accordance with another feature of the invention, the current displacer is designed as a hollow body which may be traversed by a heat exchange medium or which may have heaters in its interior. The current displacer thus serves as an additional heat exchange surface acting, if necessary, independently of the tube bundle and with an opposite direction of flow. With this arrangement, it is possible to take into account conditions which require a temporary reversal of the heat current on starting, in an interruption of the reaction because of troubles in other parts of the plant, or when the operation is started again after a brief stoppage, and which is otherwise not possible for reasons of circuitry or control, or because of lack of suitable amounts of steam.

An object of the invention is to provide an improved heat exchanger particularly designed for use in operative association with a contact furnace or other apparatus for effecting chemical reactions.

Another object of the invention is to provide such a heat exchanger which includes an annular tube bundle and associated upper and lower headers, with the tube bundle extending upwardly into the range of a propeller for circulating a heat exchange medium.

A further object of the invention is to provide such a heat exchanger in which the upper header of the tube bundle has an inner wall closely adjacent the propeller and defining a nozzle therefor.

Yet another object of the invention is to provide such a heat exchanger in which the tube bundle and its headers constitute a unit which can be removed from the installed position.

A further object of the invention is to provide such a heat exchanger including a current displacer extending upwardly through the tube bundle and filling a major portion of the free interior of the tube bundle.

Another object of the invention is to provide such a heat exchanger in which the current displacer is designed as a hollow body which may be traversed by a heat exchange medium or which may have internal heaters.

A further object of the invention is to provide such a heat exchanger in which the current displacer serves as an additional heat exchange surface which may act independently of the tube bundle and with flow counter to the direction of flow through the tube bundle.

For an understanding of the principles of the invention, reference is made to the following description of typical embodiments thereof as illustrated in the accompanying drawings.

3 BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a longitudinal sectional view through a heat exchanger embodying the invention; and

FIGS. 2, 3, 4, and 6 are partial longitudinal sectional views of the heat exchanger illustrating alternative embodiments of the lower portion of the heat exchanger.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, heat exchanger tubes 1 are arranged in circular cross section rows to provide an annular cross section upwardly oriented tube bundle. The tube bundle forms part of a heat exchanger removably mounted in a guide tube, conduit, or other passage 2 for circulation of the heat carrier of a reaction apparatus. At their upper ends, tubes 1 are connected to and communicate with a circular collecting chamber 3. While the cross sectional form of collecting chamber 3 can vary, good rounding, particularly of the inner corners 4, is important, so that inner wall 5 of collecting chamber 3 forms a nozzle closely embracing the circulating propeller 6 for one heat exchange medium. If necessary or desirable, additional current baffles 7 can be arranged at the outlet of the nozzle.

The lower collecting chamber 8 communicating with heat exchanger tubes 1 is provided for water distribution. This lower collecting chamber 8 is connected to and communicates with a current displacer 9 filling, to a great extent, the free interior of the heat exchanger and particularly the free interior of the annular cross section upwardly oriented tube bundle. For reasons of strength, the bottom wall 10 of collecting chamber 8 is connected with the head 12 of current displacer 9 by a stay or tie rod 11 which is designed as a tube. Displacer head 12, which is designed as a cone, is connected by a flexible or elastic steam connection 13 to collecting chamber 3, so that head 12 and collecting chamber 3 are in communication with each other through connection 13.

In operation, propeller 6 forces the heat carrier current past the wall 5 of collecting chamber 3 between displacer 9 and the conduit 2, as well as through the tubular stay or tie 11. The interior of displacer 9, which is in communication with collecting chambers 3 and 8, is traversed by the other heat exchange medium which also flows through the heat exchanger tubes 1. Depending on whether the heat exchanger is arranged inside or outside the reaction apparatus, which is indicated only by the bottom wall 14, a different type of admission of the heat carrier with respect to propeller 6 is provided. Thus, the admission or entry of the heat carrier to propeller 6 may be centrally or axially thereof, eccentrically thereof, or tangentially thereof.

In the embodiment of the invention shown in FIG. 2, a current displacer, comprising a central cylinder 16, a dished bottom 17, and connecting tubes 18, is installed subsequently as an additional evaporator in the heat exchanger. In this case also, the lower ends of heat exchanger tubes 1 are connected to and communicate with a circular collecting chamber 15.

In the embodiments of FIGS. 3, 4, 5 and 6, the lower ends of heat exchanger tubes 1 are also connected to and communicate with a circular collector 19. As shown in FIG. 3, the current displacer comprises a cylinder and a dished bottom head 21. In case the heat exchange medium is a liquid medium, the current displacer of FIG. 3 is provided with bafiies 22 and separate connections 23 which are welded into the dished bottom head 14. The heat exchanger and the current displacer thus can be operated independently of each other. For example, the heat exchanger can be operated with steam and the current displacer can be operated with Diphyl.

In the embodiment of FIG. 4, current displacer 24 is removably mounted through the bottom wall 14 of the reaction apparatus, by means of a flange 25, and is designed to be internally heated by a burner unit 26 therein.

In the embodiments of FIGS. 5 and 6, the heat exchange surface of the current displacer is increased, by a multiple, by dividing the current displacer into individual tubes. In FIG. 5, the individual tubes 27 are fixedly welded into the bottom 14. For forced guiding of the heating or cooling medium, distributor tubes 28 extend through the tubes 27 to define therewith an annular fiow space. Tubes 28 are open at the top and their lower ends are connected to and communicate with an inner collecting chamber 29. The annular flow passages between current displacer tubes 27 and distributor tubes 28 communicate with an outer collecting chamber 30, which is secured on bottom wall 14 in such a manner that the mentioned parts can be disassembled without interruption of the operation.

In the embodiment of FIG. 6, both the current displacer tubes 31 as well as a central main current displacer tube or conduit 32 are fixedly welded into bottom wall '14 and are provided with interchangeable electric heating units 33. The arrangement of FIG. 6 permits the differential introduction of heat, which is easy to control.

Apart from the above-mentioned possibilities and advantages of a heat exchanger embodying the invention, for operation of another apparatus, such as a contact furnace, operatively associated with the heat exchanger, it should be noted that the applicability of the contact furnace is more versatile, and that down times and production losses are reduced because the time-consuming cooling and reheating of the reaction apparatus, in case of trouble in other parts of the plant, is eliminated. Such cooling and reheating of the reaction apparatus otherwise would require from 65 to hours.

What is claimed is:

1. In a heat exchanger having an annular cross section upwardly oriented tube bundle, including a distributor element in communication with the tubes at one end of the bundle and a collector element in communication with the tubes at the opposite end of the bundle, the bundle with the collector and the distributor elements being removable from the installed position as a unit and the unit, in its operating state, being surrounded by a circulating heat exchange medium of an apparatus for effecting chemical reactions: the improvement comprising, in combination, a propeller for circulating said heat exchange medium; said heat exchanger extending upwardly into the range of said propeller; one of said distributor and collector elements comprising a circular header closely surrounding said propeller with its inner wall forming a nozzle for said propeller; and a current displacer extending upwardly through the interior of said tube bundle.

2. In a heat exchanger, the improvement claimed in claim 1, in which said current displacer is in the form of a hollow body serving as an additional heat exchange surface capable of acting independently of said tube bundle and with a flow direction opposite to that of said tube bundle.

3. In a heat exchanger, the improvement claimed in claim 2, in which said hollow body is traversed by a heat exchange medium.

4. In a heat exchanger, the improvement claimed in claim 2, including heating means mounted within said hollow body.

5. In a heat exchanger, the improvement claimed in claim 2, in which the opposite ends of said hollow body are connected to and communicate with said distributor and collector elements and forms a structural unit with said tube bundle.

6. In a heat exchanger, the improvement claimed in claim 2, in which said current displacer is fixedly mounted in said apparatus independently of said tube bundle and said distributor and collector elements.

7. In a heat exchanger, the improvement claimed in claim 2, in which said current displacer is removably mounted in said apparatus independently of said tube bundle and said distributor and collector elements.

8. In a heat exchanger, the improvement claimed in claim 1, including connections at one end of said current displacer for the supply and discharge of the heat exchange medium; and deflection means effective upon the heat exchange medium discharged or supplied through the opposite end of said current displacer.

9. In a heat exchanger, the improvement claimed in claim 1, in which said current displacer comprises plural tube assemblies each including an outer tube and an inner tube extending through said outer tube and defining therewith an annular flow space; an inner collecting chamber connected to and communicating with corresponding one ends of said inner tube; a outer collecting chamber connected to corresponding one ends of said outer tubes and communicating with said annular flow spaces; the opposite ends of said outer tubes being closed and the opposite ends of said inner tubes opening into said outer tubes; and respective connections for each of said inner and outer collecting chambers for supply and discharge of the heat exchange medium relative to said current displacer.

10. In a heat exchanger, the improvement claimed in claim 1, in Which, in dependence on Whether said heat exchanger is positioned inside or outside said apparatus, the heat exchange medium circulated by said propeller is supplied to said propeller in a respective direction selected from a direction concentric to said propeller, a direction eccentric to said propeller and a direction tangential to said propeller.

References Cited UNITED STATES PATENTS 1,936,610 11/1933 Thomas 165108 2,071,624 2/1937 Graham 165108 2,577,856 12/1951 Nelson l65108 MEYER PERLIN, Primary Examiner C. SUKALO, Assistant Examiner 

